Hamilton "Billy" Gilmour was one of the seven Gilmour brothers, three of whom played for the famed Silver Seven of Ottawa. He played on three Stanley Cup teams with the Ottawa Silver Seven in 1903, '04, and '05 and was also a member of the Cup winning Ottawa Senators in 1908-09.

Gilmour was named to the Montreal City Hockey League first All-star team in 1907 and was an Eastern Canada Amateur Hockey Association first team All-star in 1908 after finishing the season with 11 goals in 11 games. Along with his scoring prowess, Gilmour was regarded as one of the greatest stickhandlers of all time.

Gilmour served in World War I and had resided in Paris, France, prior to the outbreak of World War II before retiring to Mount Royal, Quebec.